1. Yes, you can invest in mutual funds for a period lesser than a year. However, some funds may have an exit load. Click here to learn about exit load.
2. You can start an SIP with an amount as low as Rs 100. Check out this link to view schemes according to the minimum investment value.
3. No, in this scenario you will not be charged the subscription fee of Rs 50.
4. Refer to this article for a detailed explanation.